What term describes something given over and above payment due for service?

The correct term that describes something given over and above payment due for services rendered is gratuity. Gratuity is typically a monetary amount given voluntarily by a customer or client to express appreciation for excellent service. This can often be seen in industries such as hospitality and food service, where patrons leave gratuities for wait staff or hotel staff who exceed expectations or provide exceptional service.

While a bonus refers to an extra payment given usually in the context of employment and may be contingent upon performance, and tips are often synonymous with gratuity, gratuity is a broader term that encompasses various forms of additional compensation intended to reward service quality. Commission, on the other hand, is typically a percentage of sales paid to employees or agents for services rendered — more aligned with sales performance than with the appreciation of service. Thus, the term specifically embodying the appreciation for service above what is due is gratuity.